DETROIT – General Motors Corporation yesterday outlined adjustments to the pension benefits it provides white-collar workers, the latest step in the automaker’s efforts to cut costs and turn around its North American operations.

GM said that starting January 1 it will freeze accrued pension benefits for its approximately 42,000 salaried American employees under the current defined-benefit plan formula and begin a shift toward defined-contribution plans. Defined-benefit plans promise a monthly check based on years of service and wages, while defined-contribution plans – which are increasingly the standard in the private sector – place the financial risk on workers.

The company expects the shift to result in a $1.6 billion reduction in its pension liability by end-2006 and savings on its pension expenses of about $420 million next year. In addition to the savings, the move enables GM to better estimate its benefits spending, reducing a key component of its financial risk.

Last month GM had announced it would cap health care benefits for salaried retirees – saving about $900 million in annual costs on a pre-tax basis – and said that it was evaluating ways to restructure pension benefits for white-collar employees.

A GM spokesman, Jerry Dubrowski, said that the pension changes were reviewed by the company’s board Monday. GM is in the midst of a massive restructuring after losing $8.6 billion in 2005, as the company struggles with a burdensome cost structure and steadily loses market share in America to foreign competitors. The company has pledged to close 12 manufacturing facilities and shed about 30,000 jobs.